Where Touch Signalling Fits in Panel and Machine Builds

Every mechanical pushbutton has a wear point.

It might be years away. On a panel that gets touched constantly, it might be closer than that.

Auer Signal's new Smart Dot 50 touch buttons remove that wear point, replacing the mechanical mechanism with a capacitive touch sensor. Here's what they do, and where they're likely to earn a place in a panel or machine design.

What's changed: touch instead of mechanical

The SD5BT2 (bicolour) and SD5BT3 (tricolour) are the touch-enabled additions to Auer Signal's Smart Dot 50 range: a 50 mm, M22 panel-mount device that combines signalling and input in one unit.

Instead of a mechanical switch, the button uses an ambient-adaptive capacitive touch sensor. There's no moving part to wear, stick or fail from repeated cycling.

Touch input is registered in 40 ms, with visual feedback following within 100 ms, so the response feels immediate rather than sensor-delayed.

The housing is UV-stabilised polycarbonate, rated to IP69K and IK08, and built to operate from -40°C to +70°C.

Built-in protection

Two features from Auer Signal's “Smart Protection” range are confirmed on the touch buttons specifically:

•       Active inrush current control, which limits the load placed on the controller at start-up

•       Active thermal management, which helps sustain LED lifespan under continuous operation

Both are worth noting for panels running multiple signalling devices off the same supply, where inrush current across several devices can add up.

Signalling that adapts to the task

The SD5BT2 supports five modes: steady, flash, colour-alternation, multiflash and high-intensity beat. The SD5BT3, with an extra colour to manage, runs three: steady, colour-alternation and high-intensity beat.

In practice, that means one device can indicate several different states - ready, running, fault - without needing a separate indicator for each.

Where it fits

Auer Signal lists plant construction, logistics facilities, mechanical engineering and automation, control technology, and switch cabinet construction as the primary use cases for this device. Translated into where Switches Plus customers are likely to use it:

Switch cabinet and control panel builds. A compact M22 footprint that fits standard cut-outs, with no mechanical part to fail from constant interaction, makes this worth considering anywhere a panel is opened, adjusted or reset frequently.

Machine builders and OEM equipment. Embedded directly into a machine's operator interface, the sealed, wear-free design suits equipment that runs high duty cycles without scheduled maintenance windows.

Logistics and materials handling. Sortation lines, conveyor controls and warehouse stations see frequent, repetitive input. A touch button with no mechanical wear point is built for that kind of use.

Plant construction and process environments. The IP69K rating means the device is designed to withstand high-pressure, high-temperature washdown - relevant anywhere equipment is cleaned as part of a regular cycle.

General control and status indication. Beyond direct input, the multi-mode signalling gives status feedback in a single compact device, reducing the number of separate indicators needed on a panel face.

Part of a larger platform

The SD5BT2 and SD5BT3 sit within Auer Signal's broader Smart Signaling 50 range, alongside the Smart Indicator (SI50) and Smart Tower (ST50) series. All three share the same M22 mechanical interface, so components across the range can be mixed on the same panel without re-engineering the mounting.

The wider range is also offered across three feature lines: Basic, Standard and IO-Link. The touch buttons covered here sit in the Basic line, which includes Smart Protection (the inrush current control and thermal management covered above) but not Smart Control or Smart Diagnostics, which Auer Signal reserves for its higher feature lines.

A new addition to the range

The SD5BT2 and SD5BT3 are new to Auer Signal's line-up. If you're specifying signalling or input devices into an upcoming panel or machine build and want to talk through where touch signalling might fit, get in touch with the Switches Plus team.